The general objective of this project is to examine the temporal response characteristic of the middle-and long-wavelength color vision mechanisms in normal and anomalous trichromatic humans. Human middle-and long-wavelength color vision mechanisms, having inputs from more that one cone type, show different patterns of response to temporally-modulated chromatic stimuli. The effect of variations of temporal frequency, modulation amplitude, phase, duty cycle, and wave-form of two counterphased monochromatic lights upon color perception should reveal several characteristics of the color vision mechanisms. Among these characteristics are phase relationships, response latencies and integration times.